The present invention relates to antennas and more particularly to a compact dual narrow band microstrip antenna that is particularly suited for wireless meter applications.
1. Background Art
Systems for wireless meter applications are often positioned beside buildings in urban areas and are subject to multipath reflections from other buildings. The portable reading equipment for such systems may be randomly oriented causing rotation of polarization. An antenna for a wireless meter application should be sensitive to two perpendicular orientations with good isotropic characteristics.
2. Disclosure of the Invention
A compact dual band microstrip antenna having a dielectric with a directly fed first radiating element and a spaced, coplanar, parasitic second radiating element on a first side of the dielectric, and a ground plane on an opposite second side of the dielectric is disclosed. Each radiating element has a reactance window and each radiating element is partially shorted to the ground plane by a plurality of spaced shorting posts extending through the dielectric. A uniform gap of a selected width separates the radiating elements. A feed point in the form of a hole extending through the dielectric connects to the directly fed radiating element near the gap. An opening is provided around the feed point on the side of the dielectric with the ground plane to electrically isolate the feed point from the ground plane. The ground plane is truncated.